Paper manufacture



Aug. 30, 1932.

W. E. BAIR, JR

PAPER MANUFACTURE Filed March 9, 1931 Patented Au 30, 1932 UNITED STATES PATENT OFFICE WILLIAM EDISON BAIR, JR., OF OHILLICOTHE, OHIO, ASSIGNOR TO THE MEAD CORPO- BATION, OF DAYTON, OHIO, A CORPORATION OF OHIO PAPER MANUFACTURE Application filed March 9,

This invention relates to the manufacture of paper; and one of the principal objects of the invention is to provide a method of forming paper which includes effecting controlled formation as to the opposite sides to produce a formed sheet or web of paper of hitherto .unknown and superior characteristics.

Another object of the invention is to provide such a method in the formation of a paper sheet which produces paper free from two-sidedness.

Still another object'is to provide as a superior product a paper formed with controlled body and surface characteristics.

) Another object of the invention is to provide apparatus for carrying out this method and producing such a product, which is simple in construction and effective in operation.

Other objects and advantages of the invention will be apparent from the descriptionthereof set out below and from the accompanying drawing and from the claims.

As is well known, in the manufacture of paper it is the general practice to bring the paper forming stock onto a forming Wire,

such as the traveling wire of a Fourdrinier machine, through which the water may pass leaving a web or sheet of matted fibers upon the wire. The stock constituency varies according to the operating circumstances and the end product desired, and comprises pulp made from the properly separated fibers of wood, or the like suspended in water, with admixed filler, size etc. It is a very general practice, particularly where paper of a better grade is to be made,-such for example as is used for book or magazine printing--, to admix with the fibrous suspension a considerable proportion of finely divided clay or other filler, size or other constituents; the'material's and the proportions thereof used varyingsomewhat according to the character of sheet desired. While the stock is on the forming wire some of the water escapes through the wire, the fibers remaining to form the web or sheet of paper which is subsequently removed from the wire and subjected to additional treatment, such as pressing, drying, calendering, coating, and the like. N

With particular reference to a Fourdrinier 1931. Serial No. 521,118.

machine, which type is illustrated in the drawing for purposes of'description, as the stock is flowed onto the wire there is quite a rush of water through the wire during the first few feet of travel of the stock upon the wire, and some of the finely divided filler and other finely divided constituents, and some of the finer fibers, tend to flow away with the water through the forming Wire. A large part of so much of the water of the stock as ultimately escapes through the forming wire before the formed Web is removed therefrom, escapes before the suction boxes are reached, partly-under the action of ravity and partly due to the action of the ta le rolls. The remainderof the water which is removed before the forming web is taken from the wire is removed during the remaining distance of travel of the wire, particularly while it is passing over the suction boxes and while it is passing over a suction couch roll, if such is used. As the stock flows onto the wire the greater portion of the fibers are stopped by the wire and matted thereon forming a filtering mat or web through which the remainder of the water passes or is drawn to escape through the wire side. The table rolls as they revolve carry around a film of the escaping water which tends to further wash out filler and other finer materials. Also at the suction boxes the suction tends to withdraw some of the filler, etc. with the removed water; and the same thing is true at the suction couch roll. A paper sheet as heretofore so formed ordinarily has different surface characteristics on its opposite sides. The wire side differs from the opposite or upper side both in texture and appearance; this condition of different surface characteristics bein known in the industry as twoasidedness In the formation of the sheet, with all of the water being drawn downwardly or through the sheet in one direction to escape through the wire, there results a non-homogeneous distribution of the filler, and of the fiber also, within the sheet. As a result the fibers of the upper side are generally finer than those on the wire side giving different textures and appearances to the opposite sides. Also the relative quantity of retained filler, etc. de- 100 filler. This lack of homogeneity, and the u but of two-sidedness.

exaggerating of it which attends in progressing degree upon the use of increase quantities of filler, is universally recognized in the industry as is also the fact that the practicable limit of'difi'erentiation in the two sides definitely limited, the proportion of filler that might be contained in asheet. That is, if the two-sidedness becomes too marked the sheet has no marketability and utility,or, at least, its marketability and commercial value are seriously decreased, even if not destroyed. This is especially'true with book paper, such as is used for magazines and the like. It has heretofore been ordinarily considered commercially impracticable to provide as much as 25% of filler on the dry weight of the fiber, in the finished sheet, and still secure paper suitably usable on the score Even with 20% of filler it has been very difficult to maintain the wire side and the opposite side of sufliciently similar surface characteristics. However, from a practical point of view additional quantities of filler are very desirable, for it may be generally said that the printing qualities of a sheet of a er improve as the quantity of filler carrie at the surface increases. Also, as the filler-is probably the cheapest ingredient going into the stock, from a commercial point of view it is desirable to minimize the amount of'pulp,using so much fibrous material as is necessary for giving sufiicient strength to the desired paper web, with added inclusion of filler to add body, opacity and printing quality. The present invention permits of forming a sheet of paperunder such conditions as'to produce new surface characteristics with the wire side approximating the top side characteristics. This permits of forming a sheet having a quantity of filler equal to or even greatly increased over those quantities heretofore considered practicable, with the sheet still quite free from the objectionable two-sidedness heretofore experienced.

For purposes of description, and as setting out a form of mechanism which will operate in a very satisfactory manner for the carrying on of the method of this invention and the producing of the new paper product, a conventional form of Fourdrinier paper making machine is illustrated in the drawing, largely in diagrammatic form. In the drawing the numeral 10 designates generally the frame. of the wire section of the paper mak ing machine, which frame carries the usual forming wire 11 supported by a breast roll 13, anda couch roll 14 preferably of the suction couch type. Any suitable'stock supplying inlet or means may be utilized, such means being shown diagrammatically and designated by the numeral 15. The numeral 16 conditions of dryness of the web that the liquid of the forming'material suspension is. readily absorbed by the it will carry the filler, etc. into the interwire side of the sheet stices,into,it he body of the sheet, where it will be deposited and retained, some being also retained in and on the fibers at the surface of the Web. In the type of machine shown in the drawing this definite or initial stage of formation is ordinarily reached during the passage of the forming sheet or web over the suction boxes, and the condition is indicated by the web losing the liquid appearance which it has up to that stage. .When the forming paper Web moves up to the regu lar suction box zone it gives the appearance of a pool or sheet of water suspension, but as the wire moves along-the watery sheen or glitter disappears as more water is removed, until the sheet as it assumes its initialdefi-nite form has the appearance of'a damp or moderately wet sheet. of paper. This change usually occurs as the Web passes over the suction box zone, but whatever the precise moment of its occurrence 1t 1s an easily recognized change. In actual commercial use of the invention it was found that as the initially formed sheet moved away from the last suction box it contained from 14; to 19% v of solidsor 81 to 86 of water. At this stage 'the sheet, as stated, is sufficiently definite in form and has sufiicient water absorption ca-' pacity to permit of practising the present invention. show that the above describedchange in the sheet probably takes place when sufiicient water has been removed to leave approximately 90% of water and 10% of solidsin the forming web.

When the invention is practised with th apparatus shown, the roll 20 causes the'added material to be carried up through the wire onto the wire side of the web, as arcsult of which the filler content will be embodied into the web in a proportion decreasing from the surface inwardly; The'depth to which the filler penetrates and its distribution may of course vary somewhat; butit penetrates in decreasing quantity to a considerable'distance and Without abrupt change or line of cleavage, as would be the case with a layer of coatm material applied merely to the sheet sur ace. By properlyproportioning the constituents of the additive material, as to filler, etc. the surface characteristics may be caused to more or less closelyapproach Actual commercial practices also printing,

, etc.

the characteristics of-the other side of the web, as to actual texture, susceptibility to apparent surface characteristics, In addition to deeply penetrating the sheet, the filler is also deposited and held on the surface fibers so as to whiten the wire side and give that-side the-same appearance as the other side. The effect in this respect is as if the wire side had been whitewashed to bring it up to whiteness as the other side. In actual commercial operations the appearance of the wire side of paper formed according to this invention so closely approaches in character istics the upper side that there is no evidence of-objectionable two-sidedness.

Causing the filler suspensionto pass up through the wire andonto the wire side of the web may result in somewhat weakening the finished sheet, but by the addition of suitable amounts of size orbonding agent, this tendency to weakening of the web is avoided pipe 31 and and the finished sheet will have as great strength as if it had been formed in'the heretofore usual way. No claim is made herein to this, however, since it is an improvement invented by James d A. Clark and John E. graives, Serial No. 555,757, filed August 7, 3

Asshown in the drawing a trough is positioned beneath the wire guide roll 20, which trough is suitably supportedupon the'frame of the machine, or upon the bearing support for the wire guide roll, or in any other satisfactory .way, within which is maintained a supply of suitable surfacing material. As

shown the trough is provided with a supply an overflow 32 so that during operation the height of the filler suspension in thetrough is maintained substantially con stant, and of sufiicient height to partly immerse the lower portion of the roll, and thus give a substantially uniform application to the forming web, under various operating condifipns of speed, etc. As theroll rotates it picksup a film thereon which is maintained continuously around the riding on or through this film and the suspension is thus brought into contact through the; wire with the wire side of the web, and is-incorporated therein. The paper at this point having lost a considerable portion of the original water content, as stated above, is

absorbent and readily receives the water and entrained suspended material so that a firm and homogeneous intermixture and bonding of the new material into the forming sheet,-in an amount decreasing inwardly, is secured. In satisfactory practicing of the invention the Wire guide roll of the about 10 inches'and having a surfacing of hard rubberhas been used. As stated above, flie web at the wire guide 'rollshown contains 14 519% solids and 86 to 81% water. This particular moisture content .is not thought the same appearance of roll, with the wire about of filler,

usual diameter of essential, but the moisture content may be considerably less than that specified. The moisture content after the paper web is removed from the suction'couch and as it passes.

up to the first press, has been found to var with character of stock, the suction at the couch roll, etc., and in the operation of the commercial machine on which. this invention has been practiced, the variation has been from between 'to depending on the suction at the couch roll,-with some 20-25% or less ,of solids; and as the invention is now understOOd it is believed that it may be practiced satisfactorily by applying the additive material to the initially formed web within a proportion range of solid to moisture running from 10% solid and moistureup to about 30% solid and 70% moisture.

If desired the filler suspension may be applied to the wire side of the web by using a slotted pipe, instead of a revolving roll. Also a separate wire or felt may be used for carrying the filler suspension-up for application onto the paper web, located, for example, between the suction couch and the first press roll. But no claims to these improvements are included herein since they r'zonstitute inventions of James dA. Clark'and J ohn E. Graves, as set forth in their above referred to application, and of James dA. Clark and John Traquair, as set forth in their application Serial No. 1931. v

After the added material is applied to the web the processed sheet isisubjected to addi tional suction ,by the suction couch where water and some of the surfacing material is withdrawn. The roll'20 is operated to supply an excess of suspension material so that a desired amount will be retained in the finished sheet. The paper web is then removed and transferred to a felt 40 which passes it through the several sets of presses 41 in the usual manner; after which it will be passed on through the other parts of the machine where it can receive the ordinary pressing, or such subsequent modified treatment as may be needed to produce the desired final product.

In the forming of paper sheetsthe stock ori 'nally supplied must contain a considera lygreater quantity of filler, etc.,than will appear in actual operations it has been found that to secure a finished sheet having 25% filler on the fiber content, should be added to the stock. But without the practising of this invention such proportion of filler in the finished product would give evident and'ma'rked tWo-sidedness. In the practising of this invention the percentage of filler contained in the stock has been increased to about 55%, of which about 21% remains in the finished sheet. Satisfactory results, with substantial elimination of two- -sidedness, has been secured'where the mathe ultimate product. In"

terial within the trough 30 consists of a. sus

pension of a carbonate, or other similarly acting filler in water, containing 22 pounds of carbonate filler and 3 pounds of size in 40 gallons of water. With such suspension the web will receive and retain of the additive material an amount of filler which represents from 1 to 2% of the total weight of the finished sheet. That is, with a sheet being formed from the-stock above s ecified which would give approximately 2 of filler in the finished sheet, by adding the suspension material as described an additional 1 to 2% of filler will be included with the elimination of -two-sidedness. The resulting sheet will be satisfactorily improved as to 7 its two-sidedness, even if the size is omitted.

While the process herein described, and the form of apparatus for carrying this rocess into effect, constitute preferred em odiments of the invention, it is to be understood that the invention-is not limited to this precise process and'form of apparatus, and that changes may be made in either without departin'g from the scope of the invention which is defined in the appended claims.

What is claimed is: x 1. In the manufacture of paper the method which comprises introducing paper forming stock onto a forming wire, and adding additional paper. forming material to the wire side of the forming web, while the web is still upon the forming wire.

-2. In the manufacture ofpaper the method.

which comprises introducing paper forming stock onto a forming wire, and incorporating additionalpaper forming material into the wire side of the forming web, before the forming web is withdrawn from the formmg wlre.

3. In the manufacture of pa er the method which comprises adding adgi forming materials to the web, through the wire, beyond the" suction box zone.

4. In the manufacture of paper the method which comprises adding additional paper forming materialsv to the wire side of the web, in advance of the couch roll. v

'5. In the manufacture of paper the method which comprises adding paper forming material to the -web, by depositing such material on the web through the forming wire.

6. In the manufacture of paper the method which comprises bringinga paper forming stock onto a formin "wire and removing" water therefrom to -e ect an initial definite formation of the web, and then bringing a suspension of additive material into absorb ing contact with the wire side of said sheet while in its initially formed state.

7. In the manufacture of paper the method which comprises bringing a paper forming stock onto a formi .wire and removing \water therefrom to e ectan initial definite t. f? ti n of the web, and then bringing a 'tional paper.

ing contact with said sheet through a wire. 8. In the manufactureof paper the method which comprises bringing a paper forming stock onto a. formin wire and removing water therefrom to e ect an initial definite formation of the web, and then bringing a suspension of additive material into absorbing contact with said sheet through a wire, saidadditive material comprising a suspension of filler. 9. In the manufacture of paper the method whichcomprises bringinga paper forming stock onto a forming wire and removing water therefrom, and bringing a suspension of additive material into contact with. the wire side of said sheet through said wire when the moisture content has been reduced to or less. ,10. In the manufacture of paper the method which comprises introducing a paper forming stock which includes fibrous m'aterial, filler and the like, onto a forming wire, withdrawing a portion of the suspension water and entrainedfiber, filler and :the like throu h the wire, and adding addionto a forming wire, withdrawing a portion of the suspension water and entrained fiber and the like throu h the-wire, and adding a dditionalpaper, orming material to the wire side of the resulting web to incorporate additional paper forming material into and on the wire portion of the wet web to effect a whitewashing thereof, the quantity of material thus added bein suflicient to bring the color appearance 0 the wire side up to to pro approximately the color appearanceof the opposite side of the web.

of manufacture a filled paper'contalning in excess of 10% of filler, and having-the constituent materials there- 12. As a roduct of so distributed during formation of the webas to produce substantially the same surface characteristics on both sides.

paper comprising fibrous material and incorporated filler, with the filler. decreasing.

in proportion from each surface inwardly toward the center of the web.

14. As a manufactured product, afilled paper comprising fibrous material and origi-.

nally incorporated and added filler, with v 13. As a manufacturedproducha filledthe added filler decreasing in pro ortion from the surface inwardly toward t e center of the web withoutabrupt change in the decreasing proportions. 15. In the manufacture of paper the method which comprises introducing a paper forming stock onto a forming w'ire, withdrawing a portion of the'suspension water through the wire to effect an initial definite web formation and adding additional forming material to the web while wet in its initially formed receptive state to incorporate additional forming material thereinto. In testimony whereof I hereto aflix my signature. A

WILLIAM EDISON BAIR, JR. 

